Antireflective coating compositions

ABSTRACT

The present invention discloses novel bottom anti-reflective coating compositions where a coating from the composition has an etch rate that can be regulated by the etch plate temperature.

FIELD OF INVENTION

The present invention relates to novel antireflective coatingcompositions and their use in image processing by forming a thin layerof the novel antireflective coating composition between a reflectivesubstrate and a photoresist coating. Such compositions are particularlyuseful in the fabrication of semiconductor devices by photolithographictechniques, especially those requiring exposure with deep ultravioletradiation.

BACKGROUND

Photoresist compositions are used in microlithography processes formaking miniaturized electronic components such as in the fabrication ofcomputer chips and integrated circuits. Generally, in these processes, athin coating of a film of a photoresist composition is first applied toa substrate material, such as silicon wafers used for making integratedcircuits. The coated substrate is then baked to evaporate any solvent inthe photoresist composition and to fix the coating onto the substrate.The baked and coated surface of the substrate is next subjected to animage-wise exposure to radiation.

This radiation exposure causes a chemical transformation in the exposedareas of the coated surface. Visible light, ultraviolet (UV) light,electron beam and X-ray radiant energy are radiation types commonly usedtoday in microlithographic processes. After this image-wise exposure,the coated substrate is treated with a developer solution to dissolveand remove either the radiation-exposed or the unexposed areas of thephotoresist.

There are two types of photoresist compositions, negative-working andpositive-working. When positive-working photoresist compositions areexposed image-wise to radiation, the areas of the photoresistcomposition exposed to the radiation become soluble in a developersolution (e.g. a rearrangement reaction occurs) while the unexposedareas of the photoresist coating remain relatively insoluble to such asolution. Thus, treatment of an exposed positive-working photoresistwith a developer causes removal of the exposed areas of the photoresistcoating and the formation of a positive image in the coating, therebyuncovering a desired portion of the underlying substrate surface onwhich the photoresist composition was deposited. In a negative-workingphotoresist the developer removes the portions that are not exposed.

The trend towards the miniaturization of semiconductor devices has ledboth to the use of new photoresists that are sensitive to lower andlower wavelengths of radiation, and also to the use of sophisticatedmultilevel systems to overcome difficulties associated with suchminiaturization.

High resolution, chemically amplified, deep ultraviolet (100-300 nm)positive and negative tone photoresists are available for patterningimages with less than quarter micron geometries. There are two majordeep ultraviolet (uv) exposure technologies that have providedsignificant advancement in miniaturization, and these are lasers thatemit radiation at 248 nm and 193 nm. Examples of such photoresists aregiven in the following patents and incorporated herein by reference,U.S. Pat. Nos. 4,491,628, 5,350,660, EP 794458 and GB 2320718.Photoresists for 248 nm have typically been based on substitutedpolyhydroxystyrene and its copolymers. On the other hand, photoresistsfor 193 nm exposure require non-aromatic polymers, since aromatics areopaque at this wavelength. Generally, alicyclic hydrocarbons areincorporated into the polymer to replace the etch resistance lost byeliminating the aromatic functionality. Furthermore, at lowerwavelengths the reflection from the substrate becomes increasinglydetrimental to the lithographic performance of the photoresist.Therefore, at these wavelengths antireflective coatings become critical.

The use of highly absorbing antireflective coatings in photolithographyis a simpler approach to diminish the problems that result from backreflection of light from highly reflective substrates. Two majordisadvantages of back reflectivity are thin film interference effectsand reflective notching. Thin film interference can cause swing effectsthat result in changes in critical line width dimensions caused byvariations in the total light intensity in the resist film as thethickness of the resist changes and standing waves that result in wavyfeature edges stemming from dose oscillating in the vertical direction.Reflective notching becomes severe as the photoresist is patterned oversubstrates containing topographical features, which scatter lightthrough the photoresist film, leading to line width variations, and inthe extreme case, forming regions with complete photoresist loss (forpositive resists) or unexpected photoresist masking (for negativeresists).

The use of bottom antireflective coatings provides the best solution forthe elimination of reflectivity. The bottom antireflective coating isapplied on the substrate and then a layer of photoresist is applied ontop of the antireflective coating. The photoresist is exposed imagewiseand developed. The antireflective coating in the exposed area of apositive photoresist is then typically etched and the photoresistpattern is thus transferred to the substrate.

A consequence of using an antireflective coating is its effect on etchrate selectivity as compared to the photoresist that is coated over theantireflective coating. In most single layer pattern transfer processes,an important and desired property of antireflective coatings is theirhigh etch rates in plasmas. It is well known in the semiconductorindustry that a antireflective coating that has a significantly higheretch rate than the photoresist will be better in successfully transferthe pattern after exposure and further processing steps. This, however,makes it difficult to formulate both antireflective coatings andphotoresists since both materials are based on similar types ofpolymers. While one way to control the etch property of theantireflective coating is by the selection of the polymer dye used inthe antireflective coating material, this can lead to formulation issuesin conjunction with its use with photoresists. Thus, there is a need todevelop an antireflective coating composition that has good etch rateand etch rate selectivity that is not dependent upon the polymers usedin the antireflective coatings and photoresist.

Etch selectivity is a measure of etch rate removal of one materialcompared to another. Often, the resist and the antireflective coatingare compositionally and structurally similar, which leads to a lack ofselectivity between these two materials even if the condition underwhich the antireflective coating break-through steps are performed arechanged, for example, altering plate bake temperature, enchant gases,voltage biases, pressures, and the like.

There are several approaches to creating etch selectivity differencesbetween the resist and antireflective coating. For example, by makingthe antireflective coating compositionally and structurally differentfrom the resist (by, for example, incorporating as much oxygen contentinto the antireflective coating resins), the obtained selectivitydifference is more or less constant when changing etch processconditions as mentioned above.

It is well known in the semiconductor industry that an antireflectivecoating that has a significantly higher etch rate than the photoresistwill be better in successfully transfer the pattern after exposure andfurther processing steps. There are also applications where a matchedetch rate would be desirable (no selectivity) as in the case of gatetrimming or in via filling where etch times can be reduced by selectingconditions amenable to higher etch rates during the via fill removalstep. Thus, there is a need to develop an antireflective coatingcomposition that has etch rate selectivity that can be tuned tofacilitate both pattern transfer and CD trimming or in schemes whereantireflective coatings are required to be have different selectivitiesat different steps in pattern transfer process.

The inventors have found that polymers that have a ceiling temperature(the temperature at which polymerization and monomer formation are atequilibrium) at or near the etch plate temperature in the etch chamber,the etch rate selectivity of the antireflective coating can be tuned,depending upon the requirements of the semiconductor engineer.

SUMMARY OF THE INVENTION

The present invention relates to a composition comprising a) a polymerhaving a ceiling temperature in the range from about 0° C. to about 70°C.; b) a crosslinker; and c) optionally, a cross-linking catalyst. Inaddition, the present invention relates to a coating layer from theabove composition formed on a substrate where the layer has a rate ofetch rate to etch plate temperature of at least 30 Å·min⁻¹/° C.

The polymer a) can be selected from (i) a polymer comprising repeatingunits

(ii) a polymer comprising repeating units

or(iii) a polymer comprising repeating units

where R₁, R₂, R₃, R₄, R₅, R₆, and R₂₀ are each independently selectedfrom hydrogen, halogen, and C₁₋₄ alkyl which is unsubstituted orsubstituted; R₇ is a chromophore which absorbs at any actinicwavelength; R₁₀ is —(CH₂)_(j)—OR₈ and R₈ is hydrogen, an acid labilegroup, a crosslinking site, or R₅ and R₁₀ together with the carbon atomsto which they are bound form a C₅₋₁₅ mono- or polycycloalkyl group whichis unsubstituted or substituted; R₂₂ is selected from C₁₋₄ alkyl whichis unsubstituted or substituted, alkoxycarbonyl which is unsubstitutedor substituted, or a crosslinking site; R₂₅ is C₁₋₄ alkyl which isunsubstituted or substituted, C₁₋₄ alkoxy which is unsubstituted orsubstituted, halogen, cyano, and nitro; i is 0 or 1; j is 0, 1, or 2;and z is 1 to 4, for example.

A method of forming a photoresist relief image using the abovecomposition and a coated substrate having a layer of the abovecomposition are also provided. Additionally, when a coating layer isformed from the above composition on a substrate, the layer will have arate of etch rate to etch plate temperature of at least 30 Å·min⁻¹/° C.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a composition comprising a) a polymerhaving a ceiling temperature in the range from about 0° C. to about 70°C.; b) a crosslinker; and c) optionally, a cross-linking catalyst. Inaddition, the present invention relates to a coating layer from theabove composition formed on a substrate where the layer has a rate ofetch rate to etch plate temperature of at least 30 Å·min⁻¹/° C.

The polymer a) can be selected from (i) a polymer comprising repeatingunits

(ii) a polymer comprising repeating units

or(iii) a polymer comprising repeating units

where R₁, R₂, R₃, R₄, R₅, R₆, and R₂₀ are each independently selectedfrom hydrogen, halogen, and C₁₋₄ alkyl which is unsubstituted orsubstituted; R₇ is a chromophore which absorbs at any actinicwavelength; R₁₀ is —(CH₂)_(j)—OR₈ and R₈ is hydrogen, an acid labilegroup, a crosslinking site, or R₅ and R₁₀ together with the carbon atomsto which they are bound form a C₅₋₁₅ mono- or polycycloalkyl group whichis unsubstituted or substituted; R₂₂ is selected from C₁₋₄ alkyl whichis unsubstituted or substituted, alkoxycarbonyl which is unsubstitutedor substituted, or a crosslinking site; R₂₅ is C₁₋₄ alkyl which isunsubstituted or substituted, C₁₋₄ alkoxy which is unsubstituted orsubstituted, halogen, cyano, and nitro; i is 0 or 1; j is 0, 1, or 2;and z is 1 to 4, for example.

A method of forming a photoresist relief image using the abovecomposition and a coated substrate having a layer of the abovecomposition are also provided. Additionally, when a coating layer isformed from the above composition on a substrate, the layer will have arate of etch rate to etch plate temperature of at least 30 Å·min⁻¹/° C.

The chromophore which absorbs at any actinic wavelength, R₇, can beselected from unsubstituted or substituted aromatic moieties, andunsubstituted or substituted heteroaromatic moieties. Examples ofchromophores include, but are not limited to, unsubstituted andsubstituted fluorene, unsubstituted and substituted vinylenephenylene,unsubstituted and substituted naphthalene, unsubstituted and substitutedanthracene, unsubstituted and substituted phenanthracene, unsubstitutedand substituted perylene, unsubstituted and substituted phenyl,unsubstituted and substituted benzyl, unsubstituted and substitutedchalcone, unsubstituted and substituted phthalimides, unsubstituted andsubstituted thiophenes, unsubstituted and substituted pamoic acid,unsubstituted and substituted acridine, unsubstituted and substitutedazo compounds, unsubstituted and substituted dibenzofuran, unsubstitutedand substituted benzenes, unsubstituted and substituted chrysenes,unsubstituted and substituted pyrenes, unsubstituted and substitutedfluoranthrenes, unsubstituted and substituted anthrones, unsubstitutedand substituted benzophenones, unsubstituted and substitutedthioxanthones, unsubstituted and substituted heterocyclic aromatic ringscontaining heteroatoms selected from oxygen, nitrogen, sulfur, andcombinations thereof, as well as derivatives of any of the foregoing.

In addition, according to the present invention, crosslinking sites maybe included in the polymer. Examples of such reactive groups includeepoxides (e.g., propyl epoxy), hydroxyls (e.g., hydroxyethyl), sulfonicacids, sulfonic acid esters, silyl ethers, vinyl ethers, carboxylicacids, esters of carboxylic acids, anhydrides, alkyl halides, cyanates,isocyanates, and the like. The choice of such a group is based on thebalance between its stability in the formulation and its reactivity uponthermal treatment.

As examples of the acid-labile group represented by R₈, the followingcan be considered, but is not to be considered limiting in any way: atertiary alkyl group, acetal group, substituted methyl group,1-substituted ethyl group, 1-substitution propyl group, 1-branched alkylgroup (excluding tertiary alkyl groups), silyl group, germyl group,alkoxycarbonyl group, acyl group, cyclic acid-labile group, and the likecan be given.

As examples of the tertiary alkyl group, a t-butyl group,1,1-dimethylpropyl group, 1-methyl-1-ethylpropyl group,1,1-dimethylbutyl group, 1-methyl-1-ethylbutyl group, 1,1-dimethylpentylgroup, 1-methyl-1-ethylpentyl group, 1,1-dimethylhexyl group,1,1-dimethylheptyl group, 1,1-dimethyloctyl group, and the like can begiven.

As examples of the acetal group, a methoxymethoxy group, ethoxymethoxygroup, n-propoxymethoxy group, i-propoxymethoxy group, n-butoxymethoxygroup, t-butoxymethoxy group, n-pentyloxymethoxy group,n-hexyloxymethoxy group, cyclopentyloxymethoxy group,cyclohexyloxymethoxy group, 1-methoxyethoxy group, 1-ethoxyethoxy group,1-n-propoxyethoxy group, 1-i-propoxyethoxy group, 1-n-butoxyethoxygroup, 1-t-butoxyethoxy group, 1-n-pentyloxyethoxy group,1-n-hexyloxyethoxy group, 1-cyclopentyloxyethoxy group,1-cyclohexyloxyethoxy group, (cyclohexyl)(methoxy)methoxy group,(cyclohexyl)(ethoxy)methoxy group, (cyclohexyl)(n-propoxy)methoxy group,(cyclohexyl)(i-propoxy)methoxy group, (cyclohexyl)(cyclohexyloxy)methoxygroup, and the like can be given.

As examples of the substituted methyl group, a methoxymethyl group,methylthiomethyl group, ethoxymethyl group, ethylthiomethyl group,methoxyethoxymethyl group, benzyloxymethyl group, benzylthiomethylgroup, phenacylgroup, bromophenacyl group, methoxyphenacyl group,methylthiophenacyl group, .alpha.-methylphenacyl group,cyclopropylmethyl group, benzyl group, diphenylmethyl group,triphenylmethyl group, bromobenzyl group, nitrobenzyl group,methoxybenzyl group, methylthiobenzyl group, ethoxybenzyl group,ethylthiobenzyl group, piperonyl group, methoxycarbonylmethyl group,ethoxycarbonylmethyl group, n-propoxycarbonylmethyl group,i-propoxycarbonylmethyl group, n-butoxycarbonylmethyl group,t-butoxycarbonylmethyl group, and the like can be given.

As examples of the 1-substituted methyl group, a 1-methoxyethyl group,1-methylthioethyl group, 1,1-dimethoxyethyl group, 1-ethoxyethyl group,1-ethylthioethyl group, 1,1-diethoxyethyl group, 1-phenoxyethyl group,1-phenylthioethyl group, 1,1-diphenoxyethyl group, 1-benzyloxyethylgroup, 1-benzylthioethyl group, 1-cyclopropylethyl group, 1-phenylethylgroup, 1,1-diphenylethyl group, 1-methoxycarbonylethyl group,1-ethoxycarbonylethyl group, 1-n-propoxycarbonylethyl group,1-i-propoxycarbonylethyl group, 1-n-butoxycarbonylethyl group,1-t-butoxycarbonylethyl group, and the like can be given.

As examples of the 1-substituted propyl group, a 1-methoxypropyl group,1-ethoxypropyl group, and the like can be given.

As examples of the 1-branched alkyl group, i-propyl group, sec-butylgroup, 1-methylbutyl group, and the like can be given.

As examples of the silyl group, a trimethylsilyl group,ethyldimethylsilyl group, methyldiethylsilyl group, triethylsilyl group,i-propyldimethylsilyl group, methyldi-i-propylsilyl group,tri-i-propylsilyl group, t-butyldimethylsilyl group,methyldi-t-butylsilyl group, tri-t-butylsilyl group, phenyldimethylsilylgroup, methyldiphenylsilyl group, triphenylsilyl group, and the like canbe given.

As examples of the germyl group, a trimethylgermyl group,ethyldimethylgermyl group, methyldiethylgermyl group, triethylgermylgroup, i-propyldimethylgermyl group, methyldi-i-propylgermyl group,tri-i-propylgermyl group, t-butyldimethylgermyl group,methyldi-t-butylgermyl group, tri-t-butylgermyl group,phenyldimethylgermyl group, methyldiphenylgermyl group, triphenylgermylgroup, and the like can be given.

As an example, alkoxycarbonyl means alkyl-O—C(═O)—, wherein alkyl is aspreviously described. Non-limiting examples include methoxycarbonyl[CH₃O—C(═O)—] and the ethoxycarbonyl [CH₃CH₂O—C(═O)—], benzyloxycarbonyl[C₆H₅CH₂O—C(═O)—] and the like.

As examples of the acyl group, an acetyl group, propionyl group, butyrylgroup, heptanoyl group, hexanoyl group, valeryl group, pivaloyl group,isovaleryl group, lauroyl group, myristoyl group, palmitoyl group,stearoyl group, oxalyl group, malonyl group, succinyl group, glutarylgroup, adipoyl group, piperoyl group, suberoyl group, azelaoyl group,sebacoyl group, acryloyl group, propioloyl group, methacryloyl group,crotonoyl group, oleoyl group, maleoyl group, fumaroyl group, mesaconoylgroup, campholoyl group, benzoyl group, phthaloyl group, isophthaloylgroup, terephthaloyl group, naphthoyl group, toluoyl group,hydroatropoyl group, atropoyl group, cinnamoyl group, furoyl group,thenoyl group, nicotinoyl group, isonicotinoyl group, p-toluenesulfonylgroup, mesyl group, and the like can be given.

As examples of the cyclic acid-labile group, a 3-oxocyclohexyl group,tetrahydropyranyl group, tetrahydrofuranyl group, tetrahydrothiopyranylgroup, tetrahydrothiofuranyl group, 3-bromotetrahydropyranyl group,4-methoxytetrahydropyranyl group, 2-oxo-4-methyl-4-tetrahydropyranylgroup, 4-methoxytetrahydrothiopyranyl group,3-tetrahydrothiophene-1,1-dioxide group, and the like can be given.

When R₅ and R₁₀ together with the carbon atoms to which they are boundform a C₅₋₁₅ mono- or polycycloalkyl group which is unsubstituted orsubstituted, examples of such mono- or polycycloalkyl groups includemaleic anhydride and norbornene.

Crosslinking agents are those agents which are capable of forming acrosslinked structure under the action of an acid. Some examples ofcrosslinking agents include aminoplasts such as, for example,glycoluril-formaldehyde resins, melamine-formaldehyde resins,benzoguanamine-formaldehyde resins, and urea-formaldehyde resins. Theuse of methylated and/or butylated forms of these resins is highlypreferred for obtaining long storage life (3-12 months) in catalyzedform. Highly methylated melamine-formaldehyde resins having degrees ofpolymerization less than two are useful. Monomeric, methylatedglycoluril-formaldehyde resins are useful for preparing thermosettingpolyester anti-reflective coatings which can be used in conjunction withacid-sensitive photoresists. One example isN,N,N,N-tetra(alkoxymethyl)glycoluril. Examples ofN,N,N,N-tetra(alkoxymethyl)glycoluril, may include, e.g.,N,N,N,N-tetra(methoxymethyl)glycoluril,N,N,N,N-tetra(ethoxymethyl)glycoluril,N,N,N,N-tetra(n-propoxymethyl)glycoluril,N,N,N,N-tetra(i-propoxymethyl)glycoluril,N,N,N,N-tetra(n-butoxymethyl)glycoluril andN,N,N,N-tetra(t-butoxymethyl)glycoluril.N,N,N,N-tetra(methoxymethyl)glycoluril is available under the trademarkPOWDERLINK from Cytec Industries (e.g., POWDERLINK 1174). Other examplesinclude methylpropyltetramethoxymethyl glycoluril, andmethylphenyltetramethoxymethyl glycoluril. Similar materials are alsoavailable under the NIKALAC tradename from Sanwa Chemical (Japan).

Other aminoplast crosslinking agents are commercially available fromCytec Industries under the trademark CYMEL and from Monsanto ChemicalCo. under the trademark RESIMENE. Condensation products of other aminesand amides can also be employed, for example, aldehyde condensates oftriazines, diazines, diazoles, guanidines, guanimines and alkyl- andaryl-substituted derivatives of such compounds, including alkyl- andaryl-substituted melamines. Some examples of such compounds areN,N′-dimethyl urea, benzourea, dicyandiamide, formaguanamine,acetoguanamine, ammeline, 2-chloro-4,6-diamino-1,3,5-triazine,6-methyl-2,4-diamino, 1,3,5-triazine, 3,5-diaminotriazole,triaminopyrimidine, 2-mercapto-4,6-diamino-pyrimidine,3,4,6-tris(ethylamino)-1,3,5-triazine,tris(alkoxycarbonylamino)triazine, N,N,N′,N′-tetramethoxymethylurea,methylolbenzoguanamine or alkyl ether compound thereof, such astetramethylolbenzoguanamine, tetramethoxymethylbenzoguanamine andtrimethoxymethylbenzoguanamine; 2,6-bis(hydroxymethyl)-4-methylphenol oralkyl ether compound thereof; 4-tert-butyl-2,6-bis(hydroxymethyl)phenolor alkyl ether compound thereof;5-ethyl-1,3-bis(hydroxymethyl)perhydro-1,3,5-triazin-2-one (common name:N-ethyldimethyloltriazine) or alkyl ether compound thereof;N,N-dimethyloltrimethyleneurea or dialkyl ether compound thereof;3,5-bis(hydroxymethyl)perhydro-1,3,5-oxadiazin-4-one (common name:dimethylolurone) or alkyl ether compound thereof; andtetramethylolglyoxazaldiurein or dialkyl ether compound thereof and thelike, methylolmelamines, such as hexamethylolmelamine,pentamethylolmelamine, and tetramethylolmelamine as well as etherifiedamino resins, for example alkoxylated melamine resins (for example,hexamethoxymethylmelamine, pentamethoxymethylmelamine,hexaethoxymethylmelamine, hexabutoxymethylmelamine andtetramethoxymethylmelamine) or methylated/butylated glycolurils, forexample as well as those found in Canadian Patent No. 1 204 547 to CibaSpecialty Chemicals. Other examples include, for example,N,N,N,N-tetrahydroxymethylglycoluril, 2,6-dihydroxymethylphenol,2,2′,6,6′-tetrahydroxymethyl-bisphenol A,1,4-bis[2-(2-hydroxypropyl)]benzene, and the like, etc. Other examplesof crosslinking agents include those described in U.S. Pat. No.4,581,321, U.S. Pat. No. 4,889,789, and DE-A 36 34 371, the contents ofwhich are incorporated by reference. Various melamine and urea resinsare commercially available under the Nikalacs (Sanwa Chemical Co.),Plastopal (BASF AG), or Maprenal (Clariant GmbH) tradenames.

Cross-linking catalysts include, for example, acid generators, acids,and mixtures thereof. One example of an acid generator is a thermal acidgenerator. A thermal acid generator is a compound which is not an acidbut which is converted to an acid upon heating of the photoresist film.Suitable thermal acid generators useful in the present invention includethe ammonium salts of acids where the corresponding amine is volatile.Ammonium salts of acids are prepared by neutralizing an acid withammonia or an amine. The amine may be a primary, secondary or tertiaryamine. The amine must be volatile since it must evaporate from theanti-reflective film upon heating to the temperature required tocrosslink the film. When the amine or ammonia evaporates from theanti-reflective film upon heating it leaves an acid in the film. Thisacid is then present in the anti-reflective film and is employed tocatalyze the acid hardening crosslinking reaction upon heating, unlessit becomes neutralized by a corresponding amount of a base. Photoacidgenerators may also be present in the composition and their use andtypes are well known in the art.

Examples of acid generators include onium salts, benzoin tosylate,nitrobenzyl tosylates, such as 2-nitrobenzyl tosylate, 2,4-dinitrobenzyltosylate, 2,6-dinitrobenzyl tosylate, 4-nitrobenzyl tosylate;nitrobenzyl benzenesulfonates such as 2-trifluoromethyl-6-nitrobenzyl4-chlorobenzenesulfonate, as 2-trifluoromethyl-6-nitrobenzyl 4-nitrobenzenesulfonate; phenolic sulfonate esters such asphenyl-4-methoxybenzenesulfonate,tris(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-trione,2,4,4,6-tetrabromocyclohexadienone, the alkyl esters of organic sulfonicacids, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, oxalic acid,phthalic acid, phosphoric acid, camphorsulfonic acid, alkyl and arylsulfonic acid esters, aromatic sulfonamides, alkyl and aryl phosphoricacid esters, their salts, and mixtures thereof. When benzoin tosylate isheated toluene sulfonic acid is produced by a substitution reaction.Alkyl sulfonates which produce the sulfonic acid by elimination uponheating are examples of other thermal acid generators.

Examples of acids which can be used include the non-salts of the aboveacid generators and include, for example, organic acids such as sulfonicacids (for example, alkyl and aryl sulfonic acids such as phenylsulfonicacid and para-toluenesulfonic acid), and alkyl and aryl phosphoricacids. One or more cross-linking catalysts can be used in thecomposition.

Suitable solvents for use with the inventive composition may include forexample ketones such as acetone, methyl ethyl ketone, methyl isobutylketone, cyclohexanone, isophorone, methyl isoamyl ketone, 2-heptanone4-hydroxy, and 4-methyl 2-pentanone; C₁ to C₁₀ aliphatic alcohols suchas methanol, ethanol, and propanol; aromatic group containing-alcoholssuch as benzyl alcohol; cyclic carbonates such as ethylene carbonate andpropylene carbonate; aliphatic or aromatic hydrocarbons (for example,hexane, toluene, xylene, etc and the like); cyclic ethers, such asdioxane and tetrahydrofuran; ethylene glycol; propylene glycol; hexyleneglycol; ethylene glycol monoalkylethers such as ethylene glycolmonomethylether, ethylene glycol monoethylether; ethylene glycolalkylether acetates such as methylcellosolve acetate and ethylcellosolveacetate; ethylene glycol dialkylethers such as ethylene glycoldimethylether, ethylene glycol diethylether, ethylene glycolmethylethylether, diethylene glycol monoalkylethers such as diethyleneglycol monomethylether, diethylene glycol monoethylether, and diethyleneglycol dimethylether; propylene glycol monoalkylethers such as propyleneglycol methylether, propylene glycol ethylether, propylene glycolpropylether, and propylene glycol butylether; propylene glycolalkyletheracetates such as propylene glycol methylether acetate,propylene glycol ethylether acetate, propylene glycol propyletheracetate, and propylene glycol butylether acetate; propylene glycolalkyletherpropionates such as propylene glycol methyletherpropionate,propylene glycol ethyletherpropionate, propylene glycolpropyletherpropionate, and propylene glycol butyletherpropionate;2-methoxyethyl ether (diglyme); solvents that have both ether andhydroxy moieties such as methoxy butanol, ethoxy butanol, methoxypropanol, and ethoxy propanol; esters such as methyl acetate, ethylacetate, propyl acetate, and butyl acetate methyl-pyruvate, ethylpyruvate; ethyl 2-hydroxy propionate, methyl 2-hydroxy 2-methylpropionate, ethyl 2-hydroxy 2-methyl propionate, methyl hydroxy acetate,ethyl hydroxy acetate, butyl hydroxy acetate, methyl lactate, ethyllactate, propyl lactate, butyl lactate, methyl 3-hydroxy propionate,ethyl 3-hydroxy propionate, propyl 3-hydroxy propionate, butyl 3-hydroxypropionate, methyl 2-hydroxy 3-methyl butanoic acid, methyl methoxyacetate, ethyl methoxy acetate, propyl methoxy acetate, butyl methoxyacetate, methyl ethoxy acetate, ethyl ethoxy acetate, propyl ethoxyacetate, butyl ethoxy acetate, methyl propoxy acetate, ethyl propoxyacetate, propyl propoxy acetate, butyl propoxy acetate, methyl butoxyacetate, ethyl butoxy acetate, propyl butoxy acetate, butyl butoxyacetate, methyl 2-methoxy propionate, ethyl 2-methoxy propionate, propyl2-methoxy propionate, butyl 2-methoxy propionate, methyl2-ethoxypropionate, ethyl 2-ethoxypropionate, propyl 2-ethoxypropionate,butyl 2-ethoxypropionate, methyl 2-butoxypropionate, ethyl2-butoxypropionate, propyl 2-butoxypropionate, butyl 2-butoxypropionate,methyl 3-methoxypropionate, ethyl 3-methoxypropionate, propyl3-methoxypropionate, butyl 3-methoxypropionate, methyl3-ethoxypropionate, ethyl 3-ethoxypropionate, propyl 3-ethoxypropionate,butyl 3-ethoxypropionate, methyl 3-propoxypropionate, ethyl3-propoxypropionate, propyl 3-propoxypropionate, butyl3-propoxypropionate, methyl 3-butoxypropionate, ethyl3-butoxypropionate, propyl 3-butoxypropionate, and butyl3-butoxypropionate; oxyisobutyric acid esters, for example,methyl-2-hydroxyisobutyrate, methyl α-methoxyisobutyrate, ethylmethoxyisobutyrate, methyl α-ethoxyisobutyrate, ethylα-ethoxyisobutyrate, methyl β-methoxyisobutyrate, ethylβ-methoxyisobutyrate, methyl β-ethoxyisobutyrate, ethylβ-ethoxyisobutyrate, methyl β-isopropoxyisobutyrate, ethylβ-isopropoxyisobutyrate, isopropyl β-isopropoxyisobutyrate, butylβ-isopropoxyisobutyrate, methyl β-butoxyisobutyrate, ethylβ-butoxyisobutyrate, butyl β-butoxyisobutyrate, methylα-hydroxyisobutyrate, ethyl α-hydroxyisobutyrate, isopropylα-hydroxyisobutyrate, and butyl α-hydroxyisobutyrate; solvents that haveboth ether and hydroxy moieties such as methoxy butanol, ethoxy butanol,methoxy propanol, and ethoxy propanol; and other solvents such asdibasic esters, and gamma-butyrolactone.; a ketone ether derivative suchas diacetone alcohol methyl ether; a ketone alcohol derivative such asacetol or diacetone alcohol; lactones such as butyrolactone; an amidederivative such as dimethylacetamide or dimethylformamide, anisole, andmixtures thereof. The solvent is typically present in an amount of fromabout 40 to about 95 weight percent.

Since the composition is coated on top of the substrate and is furthersubjected to dry etching, it is envisioned that the composition is ofsufficiently low metal ion level and purity that the properties of thesemiconductor device are not adversely affected. Treatments such aspassing a solution of the polymer, or compositions containing suchpolymers, through an ion exchange column, filtration, and extractionprocesses can be used to reduce the concentration of metal ions and toreduce particles.

The coating composition can be coated on the substrate using techniqueswell known to those skilled in the art, such as dipping, spincoating orspraying. The film thickness of the anti-reflective coating ranges fromabout 0.01 μm to about 1 μm. The coating can be heated on a hot plate orconvection oven or other well known heating methods to remove anyresidual solvent and induce crosslinking if desired, and insolubilizingthe anti-reflective coatings to prevent intermixing between theanti-reflective coating and the photoresist. The absorption parameter(k) of the present invention composition at either 248 nm or 193 nmtypically range from about 0.3 to about 0.9 as measured usingellipsometry. The value of the refractive index (n) typically rangesfrom about 1.25 to about 1.9. The exact values of the optimum ranges fork and n are dependent on the exposure wavelength used and the type ofapplication.

The antireflective layer is typically cured before a photoresistcomposition is applied over the antireflective composition. Cureconditions will vary with the components of the antireflectivecomposition. Thus, if the composition does not contain an acid orthermal acid generator, cure temperatures and conditions will be morevigorous than those of a composition containing an acid or acidgenerator compound. Typical cure conditions are from about 120° C. to225° C. for about 0.5 to 40 minutes. Cure conditions preferably renderthe antireflective composition coating layer substantially insoluble tothe photoresist solvent as well as an alkaline aqueous developersolution.

After such curing, a photoresist is applied over the surface of theantireflective composition. As with application of the antireflectivecomposition, the photoresist can be applied by any standard means suchas by spinning, dipping, meniscus or roller coating. Followingapplication, the photoresist coating layer is typically dried by heatingto remove solvent preferably until the resist layer is tack free.Optimally, essentially no intermixing of the antireflective compositionlayer and photoresist layer should occur.

The resist layer is then imaged with activating radiation through a maskin conventional manner. The exposure energy is sufficient to effectivelyactivate the photoactive component of the resist system to produce apatterned image in the resist coating layer as well as activate thephotoacid generator of at least a portion of the thickness ofantireflective composition layer so that photogenerated acid from thePAG of the antireflective composition is present at the antireflectivecomposition/resist coating layers interface. Typically, the exposureenergy typically ranges from about 3 to 300 mJ/cm² and depending in partupon the exposure tool and the particular resist and resist processingthat is employed. Generally, exposure doses used for typical imaging ofa resist layer will be sufficient to photoactivate an effective of acidin the underlying antireflective composition layer.

The exposed resist layer may be subjected to a post-exposure bake ifdesired to create or enhance solubility differences between exposed andunexposed regions of a coating layer. For example, negativeacid-hardening photoresists typically require post-exposure heating toinduce the acid-promoted crosslinking reaction, and many chemicallyamplified positive-acting resists require post-exposure heating toinduce an acid-promoted deprotection reaction. Typically post-exposurebake conditions include temperatures of about 50° C. or greater, morespecifically a temperature in the range of from about 50° C. to 160° C.

The exposed resist coating layer is then developed, preferably with anaqueous based developer such as an inorganic alkali exemplified bytetrabutyl ammonium hydroxide, sodium hydroxide, potassium hydroxide,sodium carbonate, sodium bicarbonate, sodium silicate, sodiummetasilicate, aqueous ammonia or the like. Alternatively, organicdevelopers can be used. In general, development is in accordance withart recognized procedures. Following development, a final bake of anacid-hardening photoresist is often employed at temperatures of fromabout 100 to 150° C. for several minutes to further cure the developedexposed coating layer areas.

It is typical to etch the antireflective coating through the openingsformed in the resist in order to transfer the photoresist pattern to theto the underlying substrate. The etching of the antireflective coatingis most often a dry etch.

Processes for the dry etching of antireflective coatings usually areaccomplished in a plasma etch system. Antireflective coating etchingplasma source gases vary considerably in composition. Some examples ofplasma source gas combinations include CHF₃/CF₄/Ar—O₂; CF₄/He—O₂; O₂/N₂;HBr/O₂; and HBr/CO₂/O₂—Ar.

In one process for etching organic antireflective coatings overlying asilicon-containing substrate, the substrate is placed into a processchamber and treated with a plasma. The plasma is generated from aprocess gas comprising oxygen and a compound selected from a group ofcompounds consisting of hydrogen and bromine-containing compounds,hydrogen and iodine-containing compounds, and mixtures thereof.Processing variables are adjusted to provide anisotropic etching of theorganic antireflective coating.

In another etching process, an anti-reflection coating overlying asemiconductor substrate is etched by employing a plasma formed from amixture of oxygen, nitrogen, and at least one inert gas. In analternative method, the antireflective coating layer may be etched byemploying a nitrogen plasma, which includes an inert gas, without anyoxygen in the plasma, although the etch rate is said to be reduced.

Another method for plasma etching a antireflective coating layeroverlying a semiconductor substrate utilizes etch chemistry provided bya plasma processing gas which includes hydrogen bromide (HBr), CO₂, andO₂, with argon or another inert gas.

Another method for plasma etching a antireflective coating layeroverlying a semiconductor substrate utilizes etch equipment which arereactive ion etching or inductive coupled-plasma etching (ICP) where ICPoffers a high-density plasma.

Another method for plasma etching a antireflective coating layeroverlying a semiconductor substrate utilizes etch chemistry which createredeposited polymer or deposition of polymers from the gas by a plasmaprocessing gas which includes hydrogen bromide and C₂F₄ or higher fluoroanalogs. Such techniques assist the anisotropy etch characteristicswhich is necessary for deep etching and are often referred to as sidewall passivation.

EXAMPLES Example 1 Synthesis of poly((t-boc 3-butene-1-ol-co-allylbenzene)-alt-sulfone)

2.3 g of 3-buten-1-ol, 7.75 g of di-tert-butyl dicarbonate and 10 mL ofmethylene chloride were placed into a 50 mL round bottom flask andmixed. After cooling the flask to −10° C., 10 mL of 5% aqueous NaOH wereadded. The mixture was allowed to warm, then heated to 40° C. for 30min. The reaction was transferred to a separatory funnel and washed with2×50 mL brine followed by 2×50 mL distilled water. The organic phase wasevaporated in a hood and the remaining oil was taken up in acetone andfiltered through a silica gel plug (20 g of Silica gel). After removingacetone, the clear transparent product t-BOC protected 3-butene-1-olweighed 1.17 grams.

2.6 grams of allyl benzene and 1.17 grams of t-BOC protected3-butene-1-ol were placed into a two-neck 50 mL round bottom flaskequipped with a magnetic stirrer, septum and a dry-ice condenser.Nitrogen flowed through the system from an inlet on the condenser whilethe condenser and reaction flask were cooled to −76° C. with acombination of dry ice and acetone. 10 mL of SO₂ was collected bycondensing SO₂ gas introduced through the condenser inlet. SO₂, allylbenzene, and t-BOC protected 3-butene-1-ol were mixed and 0.23 g oftertbutylperoxide was added via syringe thought the septum. After 20minutes, the mixture solidified. The reaction was allowed to warm toroom temperature which removes the residual SO₂. The solid was broken upwith 10 mL of methanol and poured into 50 mL of methanol. The whitesolid collected after filtration and drying in a vacuum desicator weight5.3 grams (94.4%).

Example 2

The polymer from Example 1 was formulated into an antireflective coatingcomposition (by weight—5% of the polymer from Example 1; tetrakis(methoxymethyl)glycoluril (at ⅓ the weight of the polymer from Example1); dodecylbenzenesulfonate triethylamine (at 1% weight of the polymerfrom Example 1); balance ethyl lactate. This formulation was filteredthrough a 0.2 μm filter. The optical indices of a spin-casted film fromthis antireflective coating composition were measured using VUV-VASE andfound to be at 193 nm n=1.83, k=0.70.

The antireflective coating composition of the present invention (Example2) was compared to two commercially available antireflective coatingcompositions and a photoresist to evaluate the etch rate as a functionof etch plate temperature.

The commercial antireflective coating compositions and photoresist wereused as is.

Samples of the antireflective coating compositions and photoresists wereeach spin coated onto a silicon wafer at 3000 rpm and baked at 180° C.for 60 seconds. The film thickness on each wafer, prior to etching, wasabout 2890 Å.

The coated wafers were etched under the following conditions:

Instrument—NE-5000N (ULVAC); RF power; 500 W (ISM)/100 W (bias); gasflow—CF₄/Ar/O₂ (50/150/20 sccm); pressure—5 Pa; etching time—10 seconds.Etch plate temperature ranged from 0° C. to 40° C.

Over the tested temperature range, the two commercial antireflectivecoating compositions did not show much change in the etch rate as theetch plate temperature increased. The photoresist showed a rate of etchrate to etch plate temperature of about 10 Å·min⁻¹/° C. Theantireflective coating composition of the present invention (Example 2)showed a rate of etch rate to etch plate temperature of at least 30Å·min⁻¹/° C.

Example 3 Synthesis of Poly(phthalaldehyde-co-propionaldehyde)

5 g of ortho-phthalaldehyde, 2.5 g of propionaldehyde and 17 mL ofmethylene chloride were placed into a 50 mL round bottom flask and mixedby stirring. The flask was cooled to −77° C. using a dry ice acetonebath and a solution consisting of 2 mL of 1 M BF₃ etherate and 7 mLmethylene chloride was added. The mixture was kept at −77° C. for 18 hupon which the solution solidified and stopped the magnetic stirrer. Amixture of 2 mL of pyridine in 10 mL of methylene chloride was cooled to−77° C. and then added to the above mixture with mixing. While cold, themixture was poured into 100 mL of methanol and the solid was filteredand dried to afford 5.16 g of solid white polymer. H¹-NMR revealedapproximately 3:1 phthalaldehyde:propionaldehyde incorporation into theresin. A 5% by weight solution ofpoly(phthalaldehyde-co-propionaldehyde) in PGMEA was made. A sample ofthe solution was spin-coated onto a silicon wafer at 3000 rpm and bakedat 180° C. for 60 seconds. The film thickness was 72 nm. The opticalindices of the spin casted film were measured using VUV-VASE and foundto be at 193 nm n=1.76, k=0.89.

Example 4 Synthesis of poly((t-butyl 5-norbornene-2-carboxylate-co-allylbenzene)-alt-sulfone)

5 grams of allyl benzene and 7 g of t-butyl 5-norbornene-2-carboxylatewere placed into a two-neck 50 mL round bottom flask equipped with amagnetic stirrer, septum and a dry-ice condenser. Nitrogen wasintroduced into the flask from an inlet on the condenser while thecondenser and reaction flask were cooled to −85° C. with a combinationof liquid nitrogen and acetone. 10 mL of SO₂ was collected by condensingSO₂ gas introduced through the condenser inlet. The SO₂, the allylbenzene and the t-butyl-5-norborne-2-carboxylate were mixed and a 0.2 mLof 6M tert-butyl hydroperoxide solution in decane was added via syringethought the septum. After 20 minutes, the mixture solidified. Thereaction was allowed to warm to room temperature and the residual SO₂was removed. The solid was broken up with 10 mL of methanol and pouredinto 50 mL of methanol. The white solid collected after filtration anddrying in a vacuum desiccator weight 14.5 grams (82.2%).

Example 5

The polymer from Example 4 was formulated into an antireflective coatingcomposition (by weight—5% of the polymer from Example 4; tetrakis(methoxymethyl)glycoluril (at ⅓ the weight of the polymer from Example4); dodecylbenzenesulfonate triethylamine (at 1% weight of the polymerfrom Example 4); balance ethyl lactate. This formulation was filteredthrough a 0.2 μm filter. The optical indices of the spin casted filmfrom this antireflective coating composition were measured usingVUV-VASE and found to be at 193 nm n=1.74, k=0.48.

Example 6 Synthesis of poly((t-boc 3-butene-1-co-allylbenzene-co-1-hexene)-alt-sulfone)

2.91 grams of allyl benzene and 2.22 g of 1-hexene and 2.52 g of t-boc3-butene-1 were placed into a two-neck 50 mL round bottom flask equippedwith a magnetic stirrer, septum and a dry-ice condenser. Nitrogen wasintroduced into the flask from an inlet on the condenser while thecondenser and reaction flask were cooled to −80° C. with a combinationof liquid nitrogen and acetone. 10 mL of SO₂ was collected by condensingSO₂ gas introduced through the condenser inlet. The SO₂, allyl benzene,1-hexene, and t-boc 3-butene-1 were mixed and 0.3 mL of a 6M tert-butylhydroperoxide solution in decane was added via syringe thought theseptum. After 20 minutes, the mixture solidified. The reaction wasallowed to warm to room temperature and the residual SO₂ was removed.The solid was broken up with 10 mL of methanol and poured into 50 mL ofmethanol. The white solid collected after filtration and drying in avacuum desiccator weight 10.6 grams (89.5%).

Example 7

The polymer from Example 6 was formulated into an antireflective coatingcomposition (by weight—5% of the polymer from Example 6; tetrakis(methoxymethyl)glycoluril (at ⅓ the weight of the polymer from Example6); dodecylbenzenesulfonate triethylamine (at 1% weight of the polymerfrom Example 6); balance PGME. This formulation was filtered through a0.2 μm filter.

The foregoing description of the invention illustrates and describes thepresent invention. Additionally, the disclosure shows and describes onlycertain embodiments of the invention but, as mentioned above, it is tobe understood that the invention is capable of use in various othercombinations, modifications, and environments and is capable of changesor modifications within the scope of the inventive concept as expressedherein, commensurate with the above teachings and/or the skill orknowledge of the relevant art. The embodiments described hereinabove arefurther intended to explain best modes known of practicing the inventionand to enable others skilled in the art to utilize the invention insuch, or other, embodiments and with the various modifications requiredby the particular applications or uses of the invention. Accordingly,the description is not intended to limit the invention to the formdisclosed herein. Also, it is intended that the appended claims beconstrued to include alternative embodiments.

1. A composition comprising a) a polymer having a ceiling temperature inthe range from about 0° C. to about 70° C.; b) a crosslinker whichcrosslinks with the polymer having a ceiling temperature in the rangefrom about 0° C. to about 70° C.; and c) optionally, a cross-linkingcatalyst, further where the polymer comprises a chromophore and acrosslinking functionality, and further comprises repeating units

where R₁, R₂, R₃, R₄, R₅, and R₆ are each independently selected fromhydrogen, halogen, and C₁₋₄ alkyl which is unsubstituted or substituted;R₇ is a chromophore which absorbs at any actinic wavelength; R₁₀ is—(CH₂)_(j)—OR₈ and R₈ is hydrogen, an acid labile group, a crosslinkingsite, or R₅ and R₁₀ together with the carbon atoms to which they arebound form a C₅₋₁₅ mono- or polycycloalkyl group which is unsubstitutedor substituted; i is 0 or 1; and j is 0, 1, or
 2. 2. A coating layerformed from the composition of claim 1 on a substrate, wherein saidlayer after crosslinking has a rate of etch rate to etch platetemperature of at least 30 Å·min⁻¹/° C.
 3. The composition of claim 1wherein R₇ is selected from the group of unsubstituted and substitutedfluorene, vinylenephenylene, anthracene, perylene, phenyl, benzyl,chalcone, phthalimide, pamoic acid, acridine, azo compounds,dibenzofuran, any derivatives thereof thiophenes, anthracene,naphthalene, benzene, chalcone, phthalimides, pamoic acid, acridine, azocompounds, chrysenes, pyrenes, fluoranthrenes, anthrones, benzophenones,thioxanthones, heterocyclic aromatic rings containing heteroatomsselected from oxygen, nitrogen, sulfur, and combinations thereof, aswell as derivatives thereof.
 4. The composition of claim 1 wherein R₇ isunsubstituted or substituted phenyl.
 5. The composition of claim 1wherein for a), the polymer has a ceiling temperature in the range offrom about 20° C. to about 65° C.
 6. The composition of claim 1 whereinfor a), the polymer is selected from


7. A method for forming a photoresist relief image comprising: applyingon a substrate a layer the composition of claim 1 and crosslinking thelayer to form a crosslinked layer; applying a layer ofchemically-amplified photoresist composition above said crosslinkedlayer of composition of claim
 1. 8. The method of claim 7 wherein thephotoresist composition is imaged with activating radiation and theimaged photoresist composition is treated with a developer to provide aphotoresist relief image.
 9. The method of claim 7 wherein thecrosslinked layer has a rate of etch rate to etch plate temperature ofat least 30 Å·min⁻¹/° C.
 10. A coated substrate comprising: a substratehaving thereon; a crosslinked layer of the composition of claim 1; alayer of a chemically-amplified photoresist composition above saidcrosslinked layer.
 11. The coated substrate of claim 10, wherein thecrosslinked layer has a rate of etch rate to etch plate temperature ofat least 30 Å·min⁻¹/° C.